Tag: intuition

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What is the researcher degree of freedom?

In this video, we look at what that expression “researcher degree of freedom” means. The term highlights how in quantitative research, we (have to) make a lot of choices when doing the analysis. (This actually also applies to qualitative research, but I haven’t seen the expression used in that context, yet.) These choices can affect the results we get.

I use an example to outline some of the choices in a simple regression model, and emphasize that we should try to empirically the effect of our choices on the results we report.

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How to read kernel densities

Kernel density plots like histograms are ways of summarizing a continuous variable. The height of the bars or the height of the curve tells us how likely certain values or scenarios are.

The bandwidth is a parameter to change how smooth the curve is, but it’s still a description of the same data.

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Understanding multiple imputations

In this video, we’re looking at what multiple imputations are and how they can be used to deal with missing data.

I explain why missing data can be a source of bias, using a very simple dataset to illustrate the problems. The default approach in statistical packages is to remove cases with missing values, so-called list-wise deletion. This is not necessarily a bad thing, but normally, we don’t really know why data are missing, so we don’t know if and how much bias we have.
We look at replacing missing value with the mean and using separate categories, and see that these (common) approaches are inadequate. Multiple imputations are preferable because they keep information about how uncertain we are about the imputed data. This is done by drawing from a distribution and running analyses multiple times before combining the results.

The video doesn’t go into the technicalities of multiple imputations and the different approaches there are to implement the basis idea in practice, but it should be clear that even multiple imputations cannot do magic.